1. Field of the Invention
The present invention is related generally to a data processing system and in particular to a method and apparatus for logically partitioned data processing systems. More particularly, the present invention is directed to a computer implemented method, apparatus, and computer usable program code for extending virtual real memory that is available to logical partitions by utilizing remote physical disk storage space through a reliable network connection.
2. Description of the Related Art
Increasingly large symmetric multi-processor data processing systems are frequently being partitioned and used as smaller systems. These systems are referred to as logical partitioned (LPAR) data processing systems. A logical partitioned functionality within a data processing system allows multiple copies of a single operating system or multiple heterogeneous operating systems to be simultaneously run on a single data processing system platform. A partition, within which an operating system image runs, is assigned a non-overlapping subset of the platforms resources. These platform allocable resources include one or more architecturally distinct processors and their interrupt management area, regions of system memory, and input/output (I/O) adapter bus slots. The partition's resources are represented by the platform's firmware to the operating system image.
Each distinct operating system or image of an operating system running within a platform is protected from each other, such that software errors on one logical partition cannot affect the correct operation of any of the other partitions. This protection is provided by allocating a disjointed set of platform resources to be directly managed by each operating system image and by providing mechanisms for ensuring that the various images cannot control any resources, such as memory space, that have not been allocated to that partition image. With respect to hardware resources in a logical partitioned data processing system, these resources are shared dis-jointly among various partitions. These resources may include, for example, input/output (I/O) adapters, memory DIMMs, non-volatile random access memory (NVRAM), and physical hard disk drive space. Thus, each image of the operating system, or each different operating system, directly controls a distinct set of allocable resources within the platform.